The present invention is related to a method for preventing or reducing the effects of ischemia. The ischemia may be associated with injury or reperfusion injury, such as occurs as a result of infarctions, thermal injury (burns), surgical trauma, accidental trauma, hemorrhagic shock and the like. The invention is also related to methods for preventing or reducing bacterial translocation, adult respiratory distress syndrome, adherence of blood cells and platelets to endothelial cells and pulmonary hypertension. In accordance with the present invention, these conditions are prevented or reduced by administering a dehydroepiandrosterone (DHEA) derivative.
The publications and other materials used herein to illuminate the background of the invention, and in particular cases, to provide additional details respecting the practice, are incorporated by reference, and for convenience are numerically referenced in the following text and respectively grouped in the appended bibliography.
The consequences of accidental injury represent the leading causes of death in the United States among young adults. The use of aggressive resuscitation protocols has increased the chances of a patient surviving the initial trauma event following injury. However, the development of infectious complications still represents a significant problem in these individuals. Infection and the pathologic consequences of infection contribute significantly to the morbidity and mortality observed post-injury (1, 2). Post-surgical complications in particular, represent a frequently studied model of the array of systemic inflammatory aberrations observed following all types of severe traumatic injury and major surgery (2).
It is well known that trauma patients are predisposed to life-threatening infections as a consequence of being immunologically compromised (1, 2). It is believed that the negative influences on the immune system following severe traumatic injury are similar to the protective mechanisms involved in less severe injury. Recently, it has been established that the pathophysiology of trauma/shock injury is associated with an alteration in intestinal motility that can affect the ecology of the enteric microflora and contribute to bacterial translocation (3, 4). In addition, increase permeability of the intestinal capillaries facilitates infiltration of microbial toxins that induce a systemic inflammatory syndrome mediated by potent cytokines and other bioactive substances. One of the early indicators of the systemic inflammatory syndrome is induction of an acute phase response as measured by production of acute phase reactants (4, 5).
It appears that infection, leading to sepsis and multiple organ failure, remains a major hurdle to overcome in the pathophysiologic response to trauma (6, 7). Thus far, therapeutic modalities designed to either maintain or restore organ system homeostasis in surgical and trauma patients have only been partially successful, and for the most part disappointing. The failure to develop effective therapeutic drugs in this area may be due to an inadequate base of knowledge upon which past studies were designed. A better understanding is needed of the specific components of the physiologic response to traumatic and surgical injury, such as a better distinction between host-protective inflammatory mechanisms from those that are host-injurious.
A number of studies have shown that multiple alterations in immunity occur following stress and trauma. Changes in innate host resistance to infection (3, 4), loss of memory skin test reactions (7), altered cytokine production (8), decreased B-cell function (9), and profound deficits in T cell responses (10) are among the most notable. Significant monocytosis following trauma has also been observed, along with reduced monocyte/macrophage function and increased negative regulatory macrophage activity. These later observations are associated with an increased production of immunoregulatory E series prostaglandins (11). Likewise, serum immunoglobulin and protein profiles of patients appear to be significantly altered as a consequence of trauma (12, 13).
The existence of cytokine deficits/excesses following several distinct forms of traumatic injury have been established. These reports are relevant because lymphokines and cytokines are necessary and important for the induction and regulation of almost all types of immune responses (14). Recent studies have documented the existence of altered cytokine secretion in trauma patients, as a prolonged decrease in peripheral T cell potential for IL-2 secretion and IL-2R expression (15). Wood et al. demonstrated a persistent reduction in IL-2 production in vitro by PBMC from burn patients, with even lower levels of IL-2 production by T cells from burn patients suffering from systemic sepsis (10). Additionally, high levels of circulating soluble IL-2R in serum from trauma patients have been reported (10). A depression in yIFN production has been shown to occur in burned humans (16), as well as in mice (17). A number of investigators have noticed that iatrogenic procedures (surgical manipulations, transfusions, anesthesia) induce a marked depression in the capacity of activated T cells to produce IL-2 (18). There have also been observations of increased levels of tumor necrosis factor and IL-6 following burn and mechanical trauma (2, 6). These changes persisted for up to 21 days post injury (2,6). The persistence of plasma levels of IL-6 post-trauma appears to correlate with the severity and an unsuccessful outcome of septic episodes (6), and high levels of TNF have been associated with mortality (19). The cytokine, IL-6, is a potent biologic response modifier (20, for review). High blood levels have been correlated to a pathologic response to a variety of stress stimuli, such as inflammation or infection (20). IL-6 possesses a multiplicity of effects including induction of the acute phase response (21), ELAM expression on endothelial cells and growth of plasma cells (20). IL-6 can be produced by T cells, macrophages and fibroblasts in response to appropriate stimulation (20).
The metabolic and neuroendocrine responses to injury represent components of the adaptive stress response (22). Following a given stressful event, the production of many hepatic proteins (acute phase reactants) and neuroendocrine compound is altered. These changes are believed to enhance survivability of the host. Changes in liver function are marked by elevations in plasma Zn.sup.2+, C-reactive protein, haptoglobin, .alpha.1-antitrypsin, fibrinogen, .alpha.1-acid glycoprotein and a number of heat-shock proteins. It is common to observe increased production of ACTH, cortisol and some neurotransmitters (beta-endorphin and eukephalins) with concomitant decreases in estrogen and androgen production (24,25). The altered production of many of these diverse substances can have pronounce effects. When an individual has an uneventful recovery from traumatic injury, neuroendocrine output and immune responsiveness will eventually return to normal (23, 24). In the patient sustaining severe injury, normal homeostasis of both the neuroendocrine and the immune systems become dysregulated for extended periods of time regardless of whether the patient recovers (18, 25).
Inflammatory stimuli such as thermal injury, major surgery and accidental trauma are know to be potent inducers of the HPA axis. The effect of activating the HPA is to alter normal adrenal output of steroid hormones, because glucocorticoid (GCS) production is increased at the expense of DHEAS synthesis and export. It has been clearly established that thermal injury of mice has a profound and reproducible effect on T cell function and host resistance (26). Specifically, it has been demonstrated that a number of T cell-derived lymphokines are either enhanced or repressed by the effect of thermal injury. These effects have led to the hypothesis that the change in GCS and DHEA levels is responsible for the alterations in innate and adaptive immune function. The mechanisms by which GCSs cause a depression of immunological function now appears to involve an interference with the function of certain nuclear transcription factors (27, 28). GCSs are now appreciated to exert a negative influence on gene transcription through the ability of GCS-receptor complexes to bind and inactivate the proto-oncogene product cJun, which combined with cFos activates the AP-1 transcription site (27, 28). Therefore, while the enhancement of gene transcription caused by GCS results from a classical DNA-protein interaction (29), repression of the transcription rate of other genes by this same hormone may result from specialized protein--protein (transcription factors-hormone-receptor complexes) interactions (27, 28).
Dehydroepiandrosterone (DHEA), a weak androgen, serves as the primary precursor in the biosynthesis of both androgens and estrogens (30). DHEA has been reported to play a mitigating role in obesity, diabetes, carcinogenesis, autoimmunity, neurological loss of memory (31-34), and the negative effects of GCS on IL-2 production by murine T cells (35).
Recent insight into the mechanism of action of DHEA has come from studies of ischemia-induced reperfusion injury. The clinical term used to describe the pathological process of wound extension is progressive dermal ischemia and it appears to represent the consequences of a host-initiated, time-dependent reperfusion injury. We questioned whether the degree of progressive dermal ischemia and necrosis of the skin following thermal injury in a murine model would be significantly reduced by post-burn, systemic administration of the steroid hormone DHEA (36).
DHEA and several related species of steroid hormones were evaluated for a capacity to either reduce or protect thermally injured mice against reperfusion damage of the microvasculature. Subcutaneous administration of DHEA at approximately 1-2 mg/kg/day achieved optimal protection. DHEA, as well as, 17.alpha.-hydroxy-pregnenolone, 16.alpha.-bromo-DHEA and androstenediol were all protective, whereas treatment of burned animals with other types of steroids, including androstenedione, 17.beta.-estradiol or dihydrotestosterone had no protective effect. Additionally, intervention therapy with DHEA could be withheld for up to 4 hours after burn with substantial therapeutic benefit (36, 75). It is desired to identify additional compounds which could be used for protection of patients from reperfusion damage.
It has been observed that the immediate response to a burn injury is in many ways similar to an experiment reperfusion injury in other tissues. Studies suggest that DHEA, either directly or indirectly, through its action on endothelium prevents damage to the microvasculature in reperfusion injury.
In another study the effect of DHEA on ischemia/reperfusion injury of the isolated rat cremaster muscle was evaluated. The experimental approach employed intravital microscopy to establish whether DHEA pre-treatment of rats prior to ischemia/reperfusion of the isolated muscle would protect against damage to the capillaries and venules of microcirculation. These studies indicated that in control animals, 6 hours of ischemia followed by re-flow analysis at 90 minutes and 24 hours lead to insufficient perfusion of the muscle. In DHEA pre-treated rats, 6 hours of ischemia followed by re-flow analysis at 90 minutes, 24 hours and even 4 days showed normal perfusion values in the isolated muscle. In addition, it was clear that the DHEA pre-treatment prevented sticking of neutrophils to endothelium. Additional studies in a global ischemic model demonstrated the protective effect of DHEA given intravenously after resuscitation of clinically dead rats.
It has been recognized that the maintenance of vascular integrity is an important response to injury. Complex hemostatic mechanisms of coagulation, platelet function and fibrinolysis exist to minimize adverse consequences of vascular injury and to accelerate vascular repair. Vascular endothelial and smooth muscle cells actively maintain vessel wall thromboresistance by expressing several antithrombotic properties. When perturbed or injured, vascular cells express thrombogenic properties. The hemostatic properties of normal and perturbed vascular cells has been reviewed by Rodgers (38).
Interference with the supply of oxygenated blood to tissues is defined as ischemia. The effects of ischemia are known to be progressive, such that over time cellular vitality continues to deteriorate and tissues become necrotic. Total persistent ischemia, with limited oxygen perfusion of tissues, results in cell death and eventually in coagulation-induced necrosis despite reperfusion with arterial blood. Ischemia is probably the most important cause of coagulative necrosis in human disease. A substantial body of evidence claims that a significant proportion of the injury associated with ischemia is a consequence of the events associated with reperfusion of ischemic tissues, hence the term reperfusion injury. To place reperfusion injury into a clinical perspective, there are three different degrees of cell injury, depending on the duration of ischemia:
(1) With short periods of ischemia, reperfusion (and resupply of oxygen) completely restores the structural and functional integrity of the cell. Whatever degree of injury the cells have incurred can be completely reversed upon reoxygenation. For example, changes in cellular membrane potential, metabolism and ultrastructure are short-lived if the circulation is rapidly restored.
(2) With longer periods of ischemia, reperfusion is not associated with the restoration of cell structure and function, but rather with deterioration and death of cells. The response to reoxygenation in this case is rapid and intense inflammation.
(3) Lethal cell injury may develop during prolonged periods of ischemia, where reperfusion is not a factor.
The reversibility of cell injury as a consequence of ischemia is determined not only by the type and duration of the injury, but also by the cell target. Neurons exhibit very high sensitivity to ischemia, whereas myocardial, pulmonary, hepatic and renal tissues are intermediate in sensitivity. Fibroblasts, epidermis and skeletal muscle have the lowest susceptibility to ischemic injury, requiring several hours without blood supply to develop irreversible damage.
The proximity of the endothelium to circulating leukocytes makes it an important early target for neutrophil adherence and subsequent damage to vascular and parenchymal tissue. Interaction of activated endothelial cells and neutrophils is an immediate early, and necessary, event in ischemia/reperfusion injury (39, 40). The adhesive properties of endothelium are rapidly induced by the influx of oxygenated blood. In response to oxygen, endothelial cells become activated to produce several products, including leukotriene B4 (LTB4), platelet activating factor (PAF) and P-selectin. Leukotriene B4 is a potent neutrophil chemotactic agent (41, 42). Upon activation of the endothelial cells, P-selectin is rapidly translocated from intracellular organelles to the plasma membrane, where it acts to tether circulating neutrophils and stabilize them for activation by endothelial-bound PAF (platelet activating factor), endothelium-derived cytokines and other biologically active mediators (43). Thus, the physiologic interaction between the activated endothelium and the activated neutrophil is recognized as a critical and immediate early event in reperfusion injury of organs and tissues. Other cellular and biochemical mediators of inflammation injury such as platelets, the complement cascade, and the coagulation system are also important, but come into play much later in the cascade, in a process called coagulative necrosis. Finally, monocytes, macrophages, fibroblasts and smooth muscle cell infiltration are responsible for reconstruction and replacement of dead tissue with new, vital tissue, a process called wound healing.
A popular theory postulates a role for partially reduced, and thus activated, oxygen species in initiation of membrane damage in reperfusion injury. Present evidence indicates that activated oxygen (superoxide, peroxide, hydroxyl radicals) is formed during ischemic episodes and that reactive oxygen species injure ischemic cells. Toxic oxygen species are generated not during the period of ischemia itself, but rather on restoration of blood flow, or reperfusion. Two sources of activated oxygen species have been implicated as early events in reperfusion injury, those produced intracellularly by the xanthine oxidase pathway and those which can be transported to the extracellular environment by activated neutrophils (39, 40, 44-46).
In the xanthine oxidase-dependent pathway, purines derived from the catabolism of ATP during the ischemic period provide substrates for the activity of xanthine oxidase, which requires oxygen in catalyzing the formation of uric acid. Activated oxygen species are byproducts of this reaction. The species of oxygen radicals derived from the xanthine oxidase pathway are O.sub.2.sup.- (superoxide with one electron) and H.sub.2 O.sub.2 (hydrogen peroxide with two unpaired electrons). Superoxides are generated within the cytosol by xanthine oxidase (located in the cytosol). The superoxides are then catabolized to peroxides within mitochondria by superoxide dismutase. The peroxides are further converted to water either by glutathione peroxidase, in the cytosol, or by catalase in peroxisomes. Both glutathione peroxidase and catalase comprise the antioxidant defense mechanism of most cells. The major evidence for this hypothesis rests on the ability of allopurinol, an inhibitor of xanthine oxidase, to protect against reperfusion injury in experimental models.
In the NADPH-dependent pathway, NADPH oxidase is activated to generate superoxides through reduction of molecular oxygen at the plasma membrane. The superoxides are reduced to hydrogen peroxide by superoxide dismutase at the plasma membrane or within phagolysosomes. Finally, hydrogen peroxide within phagolysosomes can be reduced in the presence of superoxides or ferrous iron to hydroxyl radicals. A third form of oxygen metabolite is mediated by myloperoxidase in the presence of chlorine to reduce hydrogen peroxide to hypochlorous acid.
The hydroxyl radical is an extremely reactive species. Mitochondrial membranes offer a number of suitable substrates for attack by OH.sup.- radicals. The end result is irreversible damage to mitochondria, perpetuated by a massive influx of Ca.sup.2+ ions. Another probable cause of cell death by hydroxyl radicals is through peroxidation of phospholipids in the plasma membrane. Unsaturated fatty acids are highly susceptible targets of hydroxyl radicals. By removing a hydrogen atom from fatty acids of cell membrane phospholipids, a free lipid radical is formed. These lipid radicals function like hydroxyl radicals to form other lipid peroxide radicals. The destruction of unsaturated fatty acids of phospholipids leads to a loss in membrane fluidity and cell death. Some investigators believe that the effects of oxidative stress cause programmed cell death in a variety of cell types.
Infarctions and traumatic injury involve many tissues, including vascular tissue. One response following traumatic injury is to shut down blood supply to the injured tissue. A purpose of this response is to protect the patient from the entry of infectious agents into the body. The severe reduction in blood supply is a main factor leading to progressive ischemia at the region of the traumatic injury. With progressive ischemia, tissue necrosis extends beyond the directly affected tissue to include surrounding unaffected tissue. This progressive ischemia plays an important role in defining the ultimate tissue pathology observed in humans as a consequence of the traumatic injury. For example, see Robson et al. (47).
One form of traumatic injury which has received a great deal of attention is thermal injury or burns. The burn wound represents a non-uniform injury, and the spectrum of injury ranges from tissue which is totally coagulated at the time of injury to tissue which is only minimally injured. Between these two extremes is tissue which is seriously damaged and not immediately destroyed, but which is destined to die. The etiology of the progressive depth of necrosis has been shown to be stasis and thrombosis of blood flow in the dermal vessels, causing ischemia and destruction of epithelial elements. This ischemia occurs for 24-48 hours following the thermal injury (47, 48). Many effects have been seen following a thermal injury, including adhesion of leukocytes to vessel walls, agglutination of red blood cells and liberation of vasoactive and necrotizing substances (48).
It has been established that burn-associated microvascular occlusion and ischemia are caused by the time dependent increase in development of microthrombi in the zone of stasis, a condition which eventually leads to a total occlusion of the arterioles and a microcirculatory standstill. Whereas margination of erythrocytes, granulocytes and platelets on venular walls are all apparent within the first few hours following thermal injury, the formation of platelet microthrombi (occurring approximately 24 hours after surgery) is believed to be responsible for creating the conditions that cause complete and permanent vascular occlusion and tissue destruction (49, 50). The formation of platelet microthrombi appears to provide the cellular basis for expanding the zone of complete occlusion and the ischemic necrosis that advances into the zone of stasis following thermal injury.
Bacterial translocation is the process by which indigenous gut flora penetrate the intestinal barrier and invade sterile tissue. Included in this process is the migration of microbial organisms to the draining mesenteric lymph nodes, spleen, liver, blood and in some instances, the lung (51, 52). This phenomenon has been documented in humans following thermal injury (53-55) and ischemia-reperfusion injury (56). DHEA has been reported to be useful in reducing or preventing bacterial translocation (36, 75). It is desired to identify additional compounds which are useful for preventing or reducing bacterial translocation.
The evidence implicating the role of neutrophils in adult respiratory distress syndrome (ARDS) is substantial but indirect (57). Some of the first suggestions that neutrophils may cause an ARDS-like picture were found in severely neutropenic patients who were infused intravenously with donor neutrophils. Occasionally, within hours of neutrophil infusion, there was an abrupt "white-out" of the lungs (by x-ray) and onset of ARDS symptoms. Numerous studies have shown that neutrophils accumulate in the lung during ARDS. For example, their presence has been demonstrated histologically. During the early phases of ARDS, the number of circulating whole blood cells transiently decreases, probably due to their abnormal pulmonary sequestration. Some neutrophils that accumulate within lung capillaries leave the vascular space and migrate into the interstitium and alveolar airspaces. In normal healthy volunteers, neutrophils account for less than 3% of the cells that can be obtained by bronchoalveolar lavage (BAL). In patients with ARDS, the percentage of neutrophils in the lavage is markedly increased to 76-85%. The accumulation of neutrophils is associated with evidence of their activation. They demonstrate enhanced chemotaxis and generate abnormally high levels of oxygen metabolites following in vitro stimulation. Elevated concentrations of neutrophil secretory products, such as lactoferrin, have been detected in the plasma of patients with ARDS. Further evidence that neutrophils actively participate in lung injury was obtained from a clinical study of patients with mild lung injury who were neutropenic for an unrelated reason (e.g., receiving chemotherapy). It was noted that lung impairment frequently worsened if a patient's hematological condition improved and circulating neutrophil counts recovered to normal levels.
Although the evidence implicating neutrophils in the genesis of human ARDS is still largely indirect, data demonstrating the importance of neutrophils in various animal models of acute lung injury is convincing. The common approach that has been used to demonstrate neutrophil independence is to deplete the animal of circulating neutrophils and measure any diminution in lung injury that occurs. Although a number of experimental models have been used to study neutrophil dependence of lung injury, only a few have been selected for discussion herein because of space limitations.
One extensively studied model is the administration of endotoxin to sheep. When endotoxin is intravenously infused into sheep, a complex set of events occurs, one of which is increased permeability of the pulmonary capillary endothelium. This is manifested by an increase in the flow of lung lymph which contains a higher-than-normal protein concentration. These changes indicate a reduction in the ability of the capillary endothelium to retain plasma proteins within the vascular space. The neutrophil dependence of the permeability injury was established when it was found that neutrophil depletion of the sheep prior to endotoxin infusion protected them. Another in vitro model of acute lung injury involves intravenous infusion of cobra venom factor into rats, which causes complement activation followed by leukoaggregation and sequestration of neutrophils within the pulmonary microvasculature. Alveolar wall damage occurs, leading to interstitial and intra-alveolar edema with hemorrhage and fibrin deposition. Again, neutrophil depletion prevented the increased pulmonary capillary leak.
Isolated, perfused rabbit or rat lungs have also been used to study mechanisms of alveolar injury under circumstances that allow improved control of the variables that affect fluid flux. When neutrophils were added to the perfusate and then stimulated, albumin leaked from the vascular compartment into the lung interstitium and alveolar airspaces. Unstimulated neutrophils or stimulus alone (e.g., phorbol myristate acetate) failed to increase alveolar-capillary permeability.
As further proof that stimulated neutrophils can independently injure lung tissue, in vitro experiments have been performed using vascular endothelial and lung epithelial cells as targets. In some reports, neutrophils have been shown to detach endothelial cells or alveolar epithelial cells from the surface of the tissue culture dish. Obviously, if such an event were to occur in vivo, the denuded surfaces would permit substantial leakage of plasma contents. Furthermore, many reports have provided clear evidence that stimulated neutrophils are able to facilitate lysis of cultured vascular endothelial cells and alveolar epithelial cells. DHEA has been reported to be useful in reducing or preventing ARDS (36, 75). It is desired to identify additional compounds which are useful for preventing or reducing ARDS.
In the United States, chronic obstructive pulmonary disease (COPD) represents the fifth most common cause of death (58). COPD also constitutes one of the most important causes of work incapacity and restricted activity (59). COPD, along with many other pulmonary diseases, causes pulmonary hypertension and right ventricular hypertrophy or cor pulmonale. Over 12 million patients in the United States alone have chronic bronchitis or emphysema, and approximately 3 million are chronically hypoxic with PaO.sub.2 &lt;60 mmHg. These patients develop hypoxic pulmonary vasoconstriction, and eventually, right ventricular hypertrophy (60). Once right ventricular hypertrophy develops, the three-year mortality rate of those patients is 60% (61, 62). Irrespective of the current management, morbidity and mortality of patients with COPD and pulmonary hypertension remain high.
One model to study pulmonary hypertension is the pulmonary vasoconstriction induced by alveolar hypoxia. Experiments in isolated animal (63) and human (64) pulmonary arteries suggest that hypoxia-induced pulmonary vasoconstriction is mediated by a direct effect of hypoxia on pulmonary vascular smooth muscle cell. It has been reported (65) that hypoxia can depolarize the pulmonary vascular smooth muscle membrane by inducing an increase in tissue Na+ and a decrease in K+. More recently, it has been reported that hypoxia can alter the membrane potential in rat main pulmonary artery smooth muscle cell and can stimulate Ca.sup.2+ influx through voltage-gated channels (66). There is strong evidence that Ca.sup.2+ entry blockade can attenuate hypoxic pulmonary vasoconstriction in isolated rat lung (67) and in patients with chronic obstructive lung disease (68). Conceivably, hypoxia may effect other membrane transport mechanisms that are involved in Ca.sup.2+ influx and/or efflux. For example, Voelkel et al. (69) speculated that hypoxia may impair Ca.sup.2+ extrusion. Farrukh et al. (70) has demonstrated that cAMP and cGMP reverse hypoxic pulmonary vasoconstriction by stimulating Ca.sup.2+ ATP-ase-dependent Ca.sup.2+ extrusion and/or redistribution. It is desired to identify compounds which are useful for treating, reducing or preventing pulmonary hypertension.
DHEA is an endogenous androgenic steroid which has been shown to have a myriad of biological activities. Araneo et al. (26) has shown that the administration of DHEA to burned mice within one hour after injury resulted in the preservation of normal immunologic competence, including the normal capacity to produce T-cell-derived lymphokines, the generation of cellular immune responses and the ability to resist an induced infection. Eich et al. (71, 72) describes the use of DHEA to reduce the rate of platelet aggregation and the use of DHEA or DHEA-sulfate (DHEA-S) to reduce the production of thromboxane, respectively.
Nestler et al. (73) shows that administration of DHEA was able in human patients to reduce body fat mass, increase muscle mass, lower LDL cholesterol levels without affecting HDL cholesterol levels, lower serum apolipoprotein B levels, and not affect tissue sensitivity to insulin. Kent (74) reported DHEA to be a "miracle drug" which may prevent obesity, aging, diabetes mellitus and heart disease. DHEA was widely prescribed as a drug treatment for many years. However, the Food and Drug Administration recently restricted its use. DHEA is readily interconvertible with its sulfate ester DHEA-S through the action of intracellular sulfatases and sulfotransferases.
Daynes et al. (75) shows that administration of DHEA was useful for the reducing or preventing progressive tissue necrosis, reperfusion injury, bacterial translocation and adult respiratory distress syndrome. However, Daynes et al. (75) further shows that the administration of DHEAS was not useful for reducing or preventing these pathological conditions.
Despite the above teaching of Daynes et al. (75), it has now been discovered that DHEAS can be used to reduce or prevent the pathophysiologic responses to the above noted pathological conditions when administered intravenously when necessary or orally at the doses described in detail below. It has also now been discovered that additional DHEA congeners can be used to reduce or prevent the pathophysiologic responses to the above noted pathological conditions.